Styrolutions reported a minor benzene, toluene leak Monday morning at its Tashmoo Ave. plant.
The company says a pinhole leak was discovered on a Nova pipeline on site during excavation work shortly before 10:30am.
Sarnia Fire and Rescue as well as Lanxess Fire Service responded as a precaution.
Area neighbours and the Ministry of Environment were notified.
The company said Monday morning the leak had been stopped and repairs were underway.